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110
Intera 5.3
Force Sensing and Selective Arm Stiffness
Now, when you move the arm in Zero G mode, you'll see that Sawyer is constrained in its
movement along the z axis (compliant in z) relative to the end effector, and rigid along the x and y
axes.
To limit the amount of force with which Sawyer pushes, check the Force or Torque Limit box for the
appropriate axis or rotation, and enter a value. Sawyer's arm will then push no more than the
defined amount of force. A practical example of this would be training Sawyer to polish a curved
surface with no more than a certain amount of force.
In Force Mode, the endpoint exerts a directional force on objects it comes in contact with, instead
of moving to a set position. The endpoint will accelerate in the force direction until it makes contact.
The force values can be either positive or negative (push or pull).
When the actual position is the same as the target position of a given Contact node, no forces are
generated. So, if you are using stiffness and you want a force to be applied when the active end-
point is in contact with a surface, you need to change the position of the Contact node to below the
surface.
Unless the active endpoint is in contact with a surface, no forces are imparted because the
commanded and actual position are essentially the same. If you are using pure impedance mode,
you will not experience the accelerations that can occur with force mode and the arm is in free
space. Both modes have the effect of imparting force on a surface in which they come into contact,
but impedance mode is more predictable.